Place chicken in a large bowl. Add onions, garlic, celery, carrots, fresh herbs, bay leaf, tomato paste, cognac, salt and pepper. Pour the wine over the mixture, followed by the olive oil, covering the mixture. Place the chicken mixture in the refrigerator for 2 hours, or overnight.
When chicken is done marinating, place a large oven safe pan on medium high. Drizzle the bottom with avocado oil. When pan is hot add chicken thighs, skin side down. Brown both sides and then place on a clean plate and set aside. While chicken is browning pre-heat the oven to 425 degrees.
Next, place the remaining marinade in a strainer that has been placed over a large bowl. Remember to keep the liquid. Add brown rice flour to the chicken pan and saute for a few minutes. Next, add in the vegetables and herbs to your pan and saute for 5 minutes. Add chicken back into the pan and cover with the reserved liquid. Bring to a boil and cover the pan with a fitted lid.
Place chicken mixture in the oven for 30 minutes.
While chicken cooks place a medium pan over medium heat. Drizzle the bottom with avocado oil and add the prosciutto. When prosciutto is crispy add in the mushrooms and continue to saute until golden brown. Sprinkle with a pinch of salt and dried thyme. Set aside until ready to use.
When chicken is cooked, remove from the oven. Taste and add salt/pepper if needed. Sprinkle the mushroom mixture over top.
Serve this dish with whipped potatoes. Enjoy!